1. Field Of The Invention
This invention relates to apparatus for aerating sewage in sewage lagoons, ponds or basins.
2. Description Of The Prior Art
Biological breakdown of sewage is a well-known technique for de-toxifying effluent, and a number of different techniques have evolved for entraining gas such as oxygen within sewage fuild or sludge for fueling its biological breakdown. One of the techniques which is used for aeration is to bubble a gas such as oxygen or air into the sewage from submerged pipes, whereupon some entrainment will occur.
It has been found that the efficiency of aeration will increase with the maximization of the gas surface area in the sewage. The efficiency also increases by mixing. The former technique requires as large a number of bubbles as is possible, and the second depends on agitation of the sewage. Both techniques are sometimes effected by bubbling the gas upwardly through a submerged cylindrical container which has baffles strategically placed either partly across or spiralling in some manner therethrough. Examples of such submerged cylindrical containers, which are commonly referred to as static aerator mixers are shown in U.S. Pat. Nos. 4,138,335; 4,169,873; 3,968,086; 3,628,775; 3,672,647; and 4,187,263.
The intent of the structure is to cause upward movement of the sewage by the pressure of differential density of gas entrained sewage, and shearing of the gas bubbles upon frictional contact with the baffles. Some agitation of the surrounding sewage has been found to occur, but in the main an unsatisfactory efficiency has resulted.
It has been found that the mixing efficiency in the basin can be increased by extending the sphere of mixing influence of the static aerator mixer installed in the basin by use of an adapter skirt as disclosed in the present invention.